In enteral feeding, a liquid nutrient solution is administered to the patient with an enteral feeding probe. The enteral nutrient solution is made available in a container that is connected to the enteral feeding probe via what is referred to as a transfer system. The enteral transfer system has a flexible probe tube having a proximal and a distal connecting piece. The distal connecting piece is connected to the feeding probe and the proximal connecting piece is connected to the container holding the nutrient solution, thus allowing the nutrient solution to flow out of the container and, via the connecting tube of the transfer system, into the feeding probe.
The container of nutrient solution is generally changed several times a day whereas in the case of the transfer system a change is recommended every 24 hours. The feeding probe can be used for as long as several months.
What have been used in the prior art to connect the connecting tube of the transfer system to the flexible tube of the feeding probe are the known luer lock connectors, thus enabling the transfer system and feeding probe to be connected together without there being any risk of the flexible tube of the feeding probe unintentionally coming loose from the flexible connecting tube of the transfer system during the administration of the nutrient solution. It is however a disadvantage that in enteral administration the known luer lock connections may pose a risk to the patient inasmuch as the luer lock connections used in enteral administration may be confused with those which are used particularly in intravenous administration and in ventilation techniques. If for example an enteral nutrient solution should inadvertently be administered via an intravenously inserted luer lock connection, there is a considerable risk to the patient.
An improvement in safety was achieved in the prior art by giving the enteral transfer system a female distal luer lock connecting piece, whereas the enteral feeding probe has a male luer lock connecting piece. Intravenous probes however have a female luer lock connecting piece, and because of this the possibility of an enteral transfer system being connected directly to the intravenous probe can be ruled out. However, because of the large number of luer lock adapters available which are offered by the various manufacturers, the possibility of mix-ups cannot be entirely ruled out.
As well as the transfer systems and feeding probes which have luer lock connections, what are also known are feeding probes which have a funnel-shaped connecting piece. Various manufacturers offer feeding probes having connecting funnels of different diameters in this case. For a connection to be able to be made to the connecting funnels of the known feeding probes, there are known in the prior art adapters of a stepped form which are generally releasably connected to the connecting tube of the transfer system by means of a luer lock connection.
The known stepped adapters have the advantage that a connection is possible to connect funnels of different diameters. The stepped adapter is plugged into the connecting funnel of the feeding probe and when this is done that section of the stepped adapter whose diameter corresponds to the diameter of the connecting funnel comes into contact with the connecting funnel. The two parts are fixed in this case by the frictional force between the circumferential surfaces of the stepped adapter and the connecting funnel.
Whereas the stepped adapter is generally made of a harder material, the connecting funnel is, as a rule, composed of a softer material to improve the transmission of force. It is a disadvantage that the retaining force between the stepped adapter and the connecting funnel may not be high enough. Particularly when nutrient solutions containing fat or grease are being used there is a risk of the connection unintentionally coming loose. Ageing effects which affect the properties of the material of the connecting funnel and its geometry may also result in a reduced retaining force.
Screwed connections, which are also used in the field of enteral feeding, are known from WO 2005/055919 A1. It is a disadvantage that the known screwed connections are not capable of general use but are confined to the particular feeding probe or transfer system which has appropriate connections.
A connecting piece of stepped form which has a plurality of sections of different diameters onto which an elastic flexible tube can be slid is known for example from U.S. Pat. No. 4,693,707. It is true that a sealed connection to flexible tubes of different diameters can be made with this known stepped adapter, but it is a disadvantage that there is a risk of the flexible tube coming loose from the connecting piece if a tractive stress is applied.
A stepped adapter for use in the field of enteral feeding is known from WO 02/051494 A1. In this case too the risk exists of the flexible tube of the feeding probe unintentionally coming loose.
U.S. Pat. No. 4,692,150 describes an arrangement which comprises a flexible probe tube having a connecting funnel and a flexible connecting tube having a stepped adapter. To secure the stepped adapter in the connecting funnel, this printed publication proposes the use of a securing band which is slid over the junction after the two parts have been plugged together, thus causing the two parts to be held together. The securing band is similarly intended to act as a protection against bacteria. It is however a disadvantage that the use of an additional securing band which has to be slid over the junction after the parts have been plugged together makes handling more difficult.